Abstract: Abstract： The accuracy of lightning rod protection range calculation is critically dependent on the rational selection of the datum plane. Based on the prevailing standards GB 50057-2010 and GB/T 50064-2014, supplemented by the Electrical Design Handbook for Power Engineering, this paper systematically contrasts the structural disparities and computational logics between independent and structural-attached lightning rods. Addressing frequent cognitive biases in engineering—such as erroneous datum selection and the conflation of regulatory systems—the study quantitatively analyzes the distortion effects of incorrect datums on protection ranges and the induced engineering risks through a typical case study. The findings offer precise datum selection strategies for architectural and power system lightning protection, effectively mitigating safety hazards and unnecessary investment.